General Description

The MAX1556/MAX1556A/MAX1557 are low-operating current (16µA), fixed-frequency step-down regulators. High efficiency, low-quiescent operating current, low dropout, and minimal (27µA) quiescent current in dropout make these converters ideal for powering portable devices from 1-cell Li-ion or 3-cell alkaline/NiMH batteries. The MAX1556 delivers up to 1.2A; has pin selectable 1.8V, 2.5V, and 3.3V outputs; and is also adjustable. The MAX1557 delivers up to 600mA; has pin

selectable 1V, 1.3V, and 1.5V outputs; and is also adjustable.

Features

♦Up to 97% Efficiency

♦95% Efficiency at 1mA Load Current

♦Low 16µA Quiescent Current

♦1MHz PWM Switching

♦Tiny 3.3µH Inductor

♦Selectable 3.3V, 2.5V, 1.8V, 1.5V, 1.3V, 1.2V, 1.0V, and Adjustable Output

♦1.2A Guaranteed Output Current (MAX1556/MAX1556A)

♦Voltage Positioning Optimizes Load-Transient Response

♦Low 27µA Quiescent Current in Dropout

♦Low 0.1µA Shutdown Current

♦No External Schottky Diode Required

♦Analog Soft-Start with Zero Overshoot Current

♦Small, 10-Pin, 3mm x 3mm TDFN Package